The present invention relates to novel 1,5'-bitetrazole compounds and processes for their production.
The present invention also relates to gas generating agents containing the 1,5'-bitetazole compounds.
The present invention further relates to foaming agents for precision molding of resins, foaming agents for reducing weight of molded articles, smoking agents for effectively diffusing chemicals such as agricultural chemicals or insecticides, and air bag gas generating agents.
It is difficult td mold crystalline resins into the shape defined by a mold, since they crystallize and shrink upon cooling after molding. Conventionally, for precision molding of crystalline resins, apparent shrinkage is empirically inhibited by using specially devised molds, which, however, cannot accomplish complete precision molding. Accordingly, additional techniques for further reducing shrinkage of molded articles are employed, which include physical blowing of gas into the core portion of molded articles (Japanese Examined Patent Publications Nos. 41264/1973 and 14968/1982), and addition of chemical foaming agents (Japanese Unexamined Patent Publications Nos. 129563/1975, 12864/1978 and 61435/1981, and U.S. Pat. No. 4,871,861). In conventional techniques, azodicarbonamide (ADCA) has been used widely for a long period of time, mainly for foam molding of resins.
ADCA, although utilized widely as a gas generating agent, is not wholly satisfactory for use in precision molding or high-foam molding for weight reduction, because it has too broad a decomposition temperature range relative to the molding temperature and causes air bubbles on the surface of molded articles, which impair the appearance. Moreover, decomposition gases and residues of ADCA contain toxic substances such as ammonia, biurea or isocyanuric acid, and thus are harmful to humans and animals and the environment. Further, the decomposition residue contaminates molds, decreasing the molding efficiency and yield of molded articles.
To solve the above problems, use of tetrazoles as gas generating agents was proposed. Tetrazoles, which decompose completely, are free from the above problems. However, since high decomposability means low stability, tetrazoles are highly sensitive to friction or other physical factors, lacking handling safety.
Further, although air bag gas generating agents and smoking agents are required to be harmless to humans and animals, safe, and odorless, conventional air bag gas generating agents and smoking agents do not fully satisfy these requirements.